Start-stop repeater system



| M. POTTS START-STOP REPEATER SYSTEM Sept. 17, 1940.

Filed Dec. 16, 1937,

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Ullllllllllll |llll7l ATTORNEY.

Patented Sept. 17, 1940 UNITED STATES PATENT OFFICE START- STOP REPEATERSYSTEM Louis M. Potts, Evanston, 11]., assignor to Teletype Corporation,Chicago, 111., a corporation of Delaware Application December 16., 1937,Serial No 180,066 12 Claims. (01. 178-70) This invention pertains toregenerative teleis placed under mechanical control of a device graphsignal repeaters and more particularly to responsive to received linesignals, while the retelegraph repeating devices of start-stop repeateris in its stop or idle condition, and in generative type in whichreproduction of signals which each of the signal impulses is repeated byis eflected by a photo-electronic system. a photo-electronic device,which starts and stops 5 In systems for comparatively slow speeds ofeach retransmitted electrical signal impulse with transmission in whichtransmission is effected great suddenness despite any mechanical slugbycomparatively long electrical impulses, an gishness of the mechanicalparts which receive, ordinary electromagnetic relay having mechanistore,and control the received signal impulse.

l0 cally controlled electrical contact points may re- The above objectsand features are attained 0 peat the impulses successfully, since thelong by utilizing mechanical principles of start-stop electricalimpulses have ample time to bring the selectors in combination withelectronic retransconnecting transmission conductor to full elecmittingmembers so arranged that the retranstrically charged condition andthereby have time mitting members are controlled through a 15 to deliverto the electromagnetic relay an elecmechanical start-stop element todetermine the 15 trical impulse sufiicient for its operation,wheretiming of retransmitted signal impulses and the upon the relayoperates to renew the current retransmitted impulses are determined inmarkstrength of the individual signal impulses, and ing or spacingnature by a mechanically moved any distortion in comparative lengths ofsucshutter element which exercises its optimum 0 cessive signal impulseswill be negligible because photo cell control by a mid-portion of itsmoveit constitutes but a small portion of the total ment where itsmechanical speed is relatively length of each signal impulse. rapid. Theshutter element further does not Withincrease of speed in signaling, theinpropagate in any repeated electrical impulse any dividual electricalimpulses become shorter, and electrical distortion resulting from anymechanithe invariable components of distortion introcal vibration orchatter resulting upon starting --duced by the electrical constants ofthe connecor stopping the mechanical shutter.

tive conductor and the mechanical constants of A system including thisinvention comprises a the repeating relay become a greater proportioncontrolling circuit having an eleotromagnet, a of a total signal impulseuntil a point is reached controlled circuit having photo-electroniccontrol where distortion of the individual signal impulses, means, and amechanical device controlled by 30 limits the speed of signaling, and toeffect still the electromagnet and controlling the admission highersignaling speeds, it becomes necessary to of light to thephoto-electronic means. While provide repeating devices which will notonly restructure is disclosed for repeating in but one new the strengthof the original signal impulse direction in the system shown, theapparatus is but will also restore the original relations of such thatit is available as a structural unit for 35 impulse lengths. Inconsideration of mechanicircuit systems operating to effect transmissioncally distorted signals, the feature of chatter in in both directionsupon a single line. the contacts of a repeating relay is a form of Theapparatus of the invention comprises mechanically produced distortionand operates to start-stop cams associated through a friction shortenthe efiective value of repeated impulses clutch with a driving motor andwith means for 40 unduly. holding the cams normally stopped, but subjectAccordingly, an object of this invention is to to control of a startingsignal 'in a controlling provide a regenerative repeater in whichoriginal line circuit. In response to a starting signal imelectricalconditions of controlling signals are pulse, the cams are started andcontinue in 5 faithfully repeated in a controlled circuit in motion fora complete cycle of revolution, which original time values as well as inrenewed is also a complete code cycle of operation, and strength, and inwhich the beginning andending then the cams come to rest in readinessfor the of the respective signals are effected with a next code cycle.minimum of transit time. Controlled by the cams is a shutter member forA still further object ofthe invention is the controlling the admissionof light into a photo- 50 provision of a photo-electric regenerativerepeatelectronic retransmitting member, the shutter ing device of simpleconstruction and operamember being such that it is controlled bythetion. cams for timing the instant of the beginning A feature of theinvention is to provide a reand ending of every retransmitted signalimgenerative p e in w ch starting mechanism pulse, but is permitted bythe cams to take a 55 transmitting position for each signal impulse inaccordance only with the electrical nature of the instantly receivedsignal impulse so that the beginning of each retransmitted impulse hasits electrical nature controlled by the instant received impulse but hasits beginning and duration controlled by the cams. A maximum abruptnessin admitting and excluding light to and from the photo-e1ectric means isattained by mechanical construction of the shutter. The start impulseand the stop impulse, which respectively precede and follow the impulsesof the intelligence code signal, also are repeated in regenerativemanner.

A more complete understanding of the invention may be had from thefollowing description taken in connection with the accompanying drawingwherein,

Fig. 1 shows a sectional view of mechanical elements of a structureillustrating this invention, taken on line l-l of Fig. 2;

Fig. 2 shows a sectional view of the mechanical elements taken on line2-2 of Fig. 1;

Fig. 3 shows a section taken at 3--3 of Fig. 1 through thephoto-electronic cabinet including a showing of an optical system and ofa retransmitting circuit;

Fig. 4 shows an enlarged section of the shutter. and

Fig. 5 illustrates a simplified illuminating system.

Referring to Fig. 1, line wire I connects transmitting substation 2 andrepeating signal receiving magnet 3 in a controlling circuit withgrounded battery 4. Repeating mean is positioned between magnet 3 andamplifier I0, whence line wire 5 completes the circuit to receivingsubstation 6. Magnet 3 has an armature II pivoted to a supporting frameby pivot I2 with retractile spring I3 and an arm I4 which constitutes afollower for a six-toothed cam I5 fixed to cam sleeve I 8, which issleeved upon a continuously rotating power shaft l'l. Shutter member 28,is pivoted about pivot rod I2 and ha a free end carrying a thin flatshutter I9 with slots l8 and is urged angularly by compression spring 2|extending between member and armature I I, and alternatively bycompression spring 22 extending between member 20 and a lug 23 formedintegrally upon arm I4. The member 20 is further positively controlledin position by engagement between a thin edge of member 20 and a similarthin edge of a lock lever 25, which is pivoted to the frame at 26, istensioned by spring 21 and which constitutes a follower for aseven-toothed cam which is fixed with cam I5 upon cam sleeve I6.Retransmltting shutter member l9 has slots I8 which open or close slots28 in cabinet 24 according to the position assumed by shutter member 28and shutter I9.

Referring to Fig. 2, power shaft I'l carries a fixed collar 32 and aspring pressed feather washer 33 between which are friction discs 34 and35 which hold frictionally a cam sleeve assembly comprising the sleeveI6, start arm 31, the sixtoothed cam I5, the seven-toothed cam 30, and aclamping nut 48. Start arm 31 engages gate 4| pivoted at 42 uponadjustable member 43, which is locked in position by clamp nut 44. Gate4| is restrained by latch 48 pivoted at 41 upon the member 43 andtensioned by compression spring 48 extending from latch 48 to member 43.Extending between latch 46 and armature II of magnet 3 is a linkagecomprising a start member 50 pivoted to the frame at 5| and engaging aplunger 52 sliding in frame part 53 and engaging at its upper end aprojection 54 on armature ll.

Cabinet 24 is constructed to be light tight with the exception of aplurality of slots 28, and contains a photo-electronic cell 8 sopositioned as to :be controlled by light reaching the interior of thecabinet through slots 28. In front of the cabinet is a thin shutter l8carried upon member 28 and provided with a plurality of slots I8 whichare related to slots 28 in such manner that in one position of shutterl9 all slots 28' will be obscured, while in the alternative position ofshutter IS, a slot I8 will be positioned in alignment with each slot 28.The width of each slot 28 exceeds the width of each slot l8 so that alimited travel of shutter I9 b permitted before any slot l8 registerswith its companion slot 28, and a similar amount of travel is permittedto the shutter l9 after the initial registration has been effected. Thisovertravel has the effect of permitting shutter 19 to attain amechanical speed before the slots I8 cut off the light by passing theedges of the slots 28. This introduces into the retransmitted signal adelay but no distortion, since the mechanical delay in cutting of! thelight can be adjusted to be equal to the mechanical delay in turning onthe light. The shutter thus moves through three operating zones in eachhalf-cycle of operation. Referring to Fig. 4 and taking center line 88of slot I8 in shutter l9 as a moving line of reference, shutter I9,while moving the center line 88 downward through light zone 8| fromposition 82 to position 84, does not vary the illumination of photocell8. While moving the center line 88 from position 84, where lower edge ofslot I8 aligns with lower edge of slot 28, through zone 83 to position88, where upper edge of slot i8 aligns with lower edge of slot 28, theshutter I9 changes the photo-cell 8 from lighted condition to darkenedcondition. The shutter moves the center line onward through dark zone 85and engages a mechanical stop at position 88, after which any bounce orvibration which does not exceed the double width zone from 88 to 89 willnot vary the dark condition of photo-cell 8.

The eflfect of shutter I9 upon photocell 8 is in-- creased by providinga plurality of slots l8, pro-' ducing a plurality of beams. The quantityof light supplied to photocell 8 is represented by a product of thewidth of slots l8 multiplied by the effective length of the slots. Whena desired quantity of light has been determined, this quantity may beadmitted to cabinet 24 by dimensioning properly the length and width ofslots l8. Providing a plurality of slots resulting in a plurality ofbeams increases the effective length of the slots and reduces therequired width thus the reducing movement required of the shutter I9.Since a minimum movement of shutter I9 facilitates its operation, theprovision of nultiple slots is desirable.

An optical system is disclosed in Fig. 3 comprising an illuminant 55, apair of condensers 56 and 51, and a collimator 58, which produces a beam59 ample to cover all of the slots I8 and 28 when the slots are inalignment and which serves thus to control the photo-cell 8 at suchtimes. a

Amplifier I0, Figs. 1 and 3, comprises valves 1 and 9, potentiometerresistor 60, and a system of three circuits; namely, a potentiometerinput circuit for grid control of valve 9, a plate circuit for valve 9which is at the same time a local potentiometer circuit for grid controlof valve 1, and an output plate circuit connected to line 5 andsubstation 6.

The potentiometer input circuit comprises a portion of potentiometerresistance 60 as a source of current, contactor 6|, conductor 66,photocell 8, conductor 62, resistor 63, and contactor 64, with apotentiometer branch conductor 65 extending to grid of valve 9.Preferably, the resistance value of resistor 63 is so chosen that amaximum change in potential of conductor 65 results in response to achange in illumination of photo-cell 8. Adjustments of contactors 6|,64, and H are such that current flows in the plate circuit of valve 9when photo-cell 8 is dark, but

does not flow when photocell 8 is illuminated.

To produce this eifect, the grid of valve 9 is at all times negativewith reference to cathode 61, being but lightly negative, due toproximity of contactors 64 and II, when photocell 8 is dark, andincreasing in negative value when photocell 8 decreases in resistance byvirtue of illumination.

The local potentiometer circuit mentioned for grid control of valve 1comprises a portion of potentiometer resistance 60 as a source ofcurrent, contactor H, cathode 61 and anode of Valve 9, conductor 12,resistor 13, and contactor 14. When, by virtue of illumination ofphoto-cell 8 and resultant control of grid 68, there is no current inthe plate circuit of valve 9, the potential of the grid 11 of valve 1 isof positive polarity with reference to the cathode 18 of valve 1 and aplate current flows in line conductor 5 of a value determined byposition of contactor I4, constituting a marking signal current insubstation 6. When, by virtue of a dark condition existing upon photocell 8, current flows as described above in the local potentiometercircuit including valve 9 and resistor 13, a potential condition isestablished upon potential branch conductor 15 and therefore upon grid11, such that the plate current of valve 1 is suppressed. In review, asignal of marking nature in a system including the invention exemplifiedin the drawing includes a marking signal current in the transmittingsubstation 2 and line conductor I, an energized condition of magnet 3,the shutter l9 in the position shown, slots I8 and 28 in alignment asshown in Fig. 3, an illuminated condition of photo-cell 8, estoppel ofcurrent in plate circuit of valve 9, and a plate currentin valve 1constituting a marking signal current in line 5 and substation 6. For asignal of spacing nature, with shutter 19 closed and with photo-cell 8dark, transmission is effected as follows:' Resistance of photocell 8 isat its higher value and potential from resistor 60 through contactor 64and resistor 63 eifects a potential upon grid of valve 9 to render thevalve conducting and the grid of valve 1 is rendered negative, renderingthe plate circuit of valve 1 non-conducting and estopping current fromline conductor 5, producing at substation 6 a signal of spacing nature.

In Fig. 5 an alternative illuminating system is illustrated, in which aconcentrated illuminant 88 is positioned near the shutter I9 and theoptical system is omitted.

The operation of the mechanical system is as follows: An interruption ofcurrent at transmitter 16 at substation 2 of the controlling line I willcause deenergization of signal receiving magnet 3, which will releasearmature ll permitting cam follower H to drop into the path of thesix-toothed cam I5 and permitting the armature extension 54 to shift theplunger 52, which will operate lever 58 to cause operation, in turn, oflatch 46, which will release gatell to release start arm 31, and thus topermit the rotation of cam sleeve I6 and its cams I5 and 30 by the powerof shaft I1 through friction of discs 34 and 35. Operation of armature lI, when released by deenergized magnet 3, also compresses spring 2| andrelaxes spring 22, but transmitting shutter member 20 resists the springpressure because it is locked by lever 25, which is in the path of theseven-toothed cam 30, which cam now is starting. The first mechanicalaction of the cam sleeve l6 and its cams is to operate the lock lever 25by cam 30 thereby releasing shutter member 20 which moves shutter l9 andrepeats the signal from transmitting station 2 to the receiving station6 by controlling the photo-cell 8, which in turn controls valves 9 and1, which produces a spacing signal in line conductor 5, as describedabove. The operation of lock lever 25 is momentary because of the smallarcuate dimension of the lobes of the toothed cam 30, and member 26immediately is relocked. In operating to unlock the shutter member 20,looking member 25 permits release of the member suddenly at the instantwhen the end of lever 25 leaves the end of member 20. The impulse fromstation 2 now being repeated to station 6, thus has been determined inpoint of time solely by the movement of the cam 30 acting through lever25 to release member 20, but its electrical nature whether a markingcurrent in line 5, because valve 1 is conducting, or whether a spacingcurrent in line 5, because valve 1 is non-conducting, is determinedsolely by the position of the armature II which has been controlledsolely by the signal received in magnet 3 under control of station 2.

At this time, lever 25 again projects into the path of teeth'of cam 30,arm l4 projects into the path of cam l5, and the next action is theengagement of a tooth of cam 15 with its follower arm I l wherebyarmature II is moved toward or against its controlling magnet 3. Thisaction occurs six times in a cycle, each such occurrence at about themiddle of six of the code impulses; namely, first, second, third,fourth, and fifth impulses and the stop impulse of the code. In eachinstance, armature II will be heldby magnetism of energized magnet 3 ifthe instant signal be a closed circuit at station 2, but in eachinstance armature II will be released by the passing of tooth of cam l5from follower arm 14 and armature II will be Withdrawn from deenergizedmagnet 3 by spring i3 if the instant signal at transmitting station 2 besuch that the transmitting station 2 is open circuit to deenergizemagnet 3. In each such instance, action of follower l4 byv cam l5 andretention or release of armature II by magnet 3 will be followed byoperation of lock lever 25 by 'cam 38, which will permit shutter member20 to operate the shutter to open or close the light cabinet 24accordingly as magnet 3 has retained armature II or has releasedarmature ll, urging shutter member 26 downward or upward when releasedby lever 25.

Thus there is provided a regenerative repeating mechanism having a smallnumber of mechanical parts andno electricalcontacts, whose parts arecontrolled by electro-mechanical means and the motion of whose partscontrol the illumination or darkening of the photo-electric cell 8 incode manner in response to received signals.

The application of the photo-electronic retransmission has been madehere with reference to a specific type of mechanical control device foroperating the shutter member 20 and shutter l9. It will be understoodthat many modified forms of shutter and shutter controlling member maybe designed to cooperate with variant forms of mechanical controllingdevices.

What is claimed is:

1. In a regenerative repeater, signal receiving means, a photo-shutterhaving a closed and open position, means to determine the succession ofopen and closed positions of the shutter according to the operation ofthe signal receiving means, a rotary start-stop timing member startedinto rotation by said signal receiving means responsively to an initialsignal of a group of signals, and means responsive to said timing memberto determine the actual time of the change from open position of saidshutter to close position of said shutter or vice versa, controlled bysaid timing means.

2. In a signal receiving system, means to transmit code signals, timingmeans started by said signals at the beginning of each code signal andoperating independently for the remainder of the signal, a photo-shutterhaving an open and closed position, means controlled by the signal todetermine the position of the shutter for each element of the signal,means to determine the time of change from open to closed and vice versacontrolled by the timing means, means to produce a beam of radiantenergy, means to modulate the beam by said shutter, a photo-electriccell activated by said beam, and means to transmit electric telegraphsignals according to the activation of the photo-electric cell.

3. In a regenerative repeater, signal receiving means, means to produceand extinguish a beam of light under the control of the receiving means,means normally at rest and started into rotation by said signalreceiving means in response to a starting signal to time the intervalsbetween producing and extinguishing the beam, a photoelectric deviceactivated by said beam, and means to transmit electrical signalscontrolled according to the operation of the photo-electric device.

4. In a telegraphic repeating device, an armature controlled by receivedelectrical signals, a photo-electronic member having a shutterelastically articulated to said armature, and camcontrolled mechanisminitially responsive to said armature and operating to' render saidshutter operable by said armature ata predetermined instant.

5. In a telegraphic repeating device, an armature controlled by receivedelectrical signals, a photo-electronic member having a shutter, elasticmeans connecting said shutter and said armature, and cam-controlledmechanism initially responsive to said armature and operating to rendersaid shutter operable by said armature through said elastic means.

6. In a telegraphic repeating device, a signal receiving magnet, anarmature for said magnet, a photo-electronic retransmitting memberhaving a shutter, a tension member connecting said armature and saidshutter to operate said shutter in response to movement of saidarmature, and a locking member engaging said shutter to restrain saidshutter whereby an instantly received signal is stored in said tensionmember.

7. In a telegraphic repeating device, an armature controlled bysuccessive received signals, a photo-electronic member having a controlmember elastically articulated to said armature, and cam-controlledmechanism rendering said control member responsive to said armature atsuccessive instants of beginning of a plurality of electricalretransmission time intervals.

8. In a telegraphic repeating device, an armature controlled bysuccessive received signals, a photo-electronic retransmitting memberhaving a movable shutter, means selectively controlled by said armatureand acting to urge said shutter to move, a locking member engaging andrestraining said shutter, and means operating said locking member torelease said shutter repeatedly.

9. In a telegraphic repeating device, an armature responsive tosuccessive received signal impulses, a photo-electronic retransmittingmember having a controlling shutter elastically connected to saidarmature to follow movements of said armature, and cam controlledmechanism engaging said shutter and restraining said shutter after saidarmature has been shifted and until a mechanically predeterminedinstant.

10. In a telegraphic repeating device, a receiving member responsive toreceived electrical signals, a photo-electronic retransmitting membercontrolled by said receiving member, a rotary member responsive to saidreceiving member to begin rotation, and means associating said rotarymember and said retransmitting member to control said retransmittingmember repeatedly during each rotation to begin retransmission ofsuccessive received signals.

11. In a telegraphic repeating device, a photoelectronic retransmitter,a timing member therefor, a restraining member engaging and restrainingsaid timing member, an armature controlled by received signals, andmeans operated by said armature and acting to control said timing memberand said photo-electronic retransmitter.

12. In a telegraph transmitting device, a photocell, a shuttercontrolling the illumination thereoi, and means to operate said shutterthrough a preliminary zone of motion prior to varying the illuminationof said cell, through an intermediate zone of motion while varying theillumination of said cell, and through a final zone of motion aftervarying the illumination of said cell.

Louis M. ro'rrs.

